The present invention relates to the field of photography and, more specifically, to processing apparatus for treating a sheet-like film unit with a low viscosity processing liquid by effecting immersion of the film unit in the liquid for a desired processing interval and then removing it therefrom.
Immersion treatment of a film unit is used in a variety of photographic processes such as developing, fixing, washing, and combination processes utilizing monobath solutions. While the present invention focuses on treating an exposed self-developing film unit with an aqueous alkaline processing liquid to initiate a developmemt and diffusion transfer process, it will become apparent later that the invention is not limited in its scope to this particular application.
The prior art is replete with processing apparatus for facilitating immersion treatment of a sheet-like film unit. Typically, such apparatus include a container holding a supply of processing liquid; means for locating the film unit at an immersed treatment position within the liquid; and means for squeegeeing excess liquid from the film unit in conjunction with its removal from the container.
One common type of apparatus for processing self-developing film units comprises a liquid holding tray into which the film unit is inserted along guideways to a submerged treatment position, and a pair of pressure-applying rollers between which the wet film unit is advanced for removing it from the tray while at the same time squeegeeing excess fluid therefrom. Some apparatus are configured to process a self-developing film unit embodied as a single sheet laminate structure having both photosensitive and image receiving layers therein. Other processing apparatus are configured to process film units wherein the image receiving layer is on a separate support sheet which is not immersed in the liquid but is fed through the pressure rollers in superposition with a liquid treated photosensitive sheet to form a diffusion transfer film unit. For representative examples of this type of processing apparatus, see commonly assigned U.S. Pat. Nos. 3,288,609; 3,405,617; 3,405,618; 3,418,912; and U.S. Pat. Nos. 4,223,991 and 4,361,392.
Another type of immersion processing apparatus is disclosed in commonly assigned U.S. Pat. Nos. 2,873,660 and 3,255,099; and 3,659,512.
In FIGS. 1-7 of the '660 patent, the apparatus comprises a compressibly deformable, vertically oriented, liquid container having a wiper blade type of squeegee device at its upper film entry end. By applying compressive pressure to the opposite ends of the squeegee device, the interdigitated wiper blades bow out allowing insertion of the film unit into the liquid within the container without interference from the wiper blades. At column 3, lines 68 to 74, it is suggested that the container does not have to be completely filled with the liquid but rather the side walls of the container may be compressed to reconfigure its interior volume and thereby raise the level of the liquid to completely cover that portion of the film unit that is to be immersed for treatment. Following immersion for the prescribed time, the film is manually pulled through the wiper blades to squeegee off excess fluid as the film unit is removed from the container. In other embodiments, shown in FIGS. 8 and 12 through 14, the vertically disposed container is divided into an upper film unit receiving chamber and a lower communicating liquid reservoir. After the film unit is inserted into the upper receiving chamber, the container is inverted to flood the receiving chamber with liquid from the reservoir. Following imbibition, the container is turned upright to drain the liquid back into the reservoir. The wet film unit then is manually pulled through the squeegee device to remove excess fluid.
Commonly assigned U.S. Pat. No. 3,659,512 discloses a self-developing camera having a disposable resilient bladder, holding a supply of processing liquid which is connected to a vertically disposed film treatment chamber. The exposed film unit is inserted into the chamber which is then flooded with the liquid by compressing the bladder (reservior) so it acts as a pump. Following imbibition, the pressure is released and the liquid is drained from the chamber by siphoning action of the bladder.
Immersion processing apparatus known in the prior art have several drawbacks that tend to make them somewhat inconvenient and awkward to use and, in some instances, require construction that is relatively expensive.
For example, in film development applications, many prior art apparatus require the user to handle an aqueous alkaline processing liquid when filling the container with fresh liquid and emptying it of deteriorated liquid, or when changing a disposable liquid container. Because of the caustic nature of the processing liquid, care must be taken to avoid spills or contact with the skin. Also, the user must be familiar with procedures for safely neutralizing the liquid should a spill or skin contact occur.
Another disadvantage is that the squeegee devices (e.g., rollers or wiper blades) act directly on the wet film unit and become coated with the processing liquid. If the processing apparatus is not in continuous use, the liquid tends to dry out and form a residue crust on the squeegee device requiring periodic disassembly and cleaning. Also, a liquid residue can build up on the walls and guide structure of the film unit receiving chamber after the liquid is drained therefrom in processing apparatus that use the receiving chamber/reservoir construction.
Those prior art processing apparatus which employ wiper blades for removing excess liquid from the film unit have a further disadvantage in that the blades apply a shearing force to the outside surfaces of the film unit. In certain types of film units, such a force may abrade or scratch the outer surface or may cause dislocations in interior layers that soften and/or swell upon absorbing the processing liquid.
Certain photographic processing liquids tend to deteriorate as a result of aerial oxidation caused by prolonged atmospheric contact with the liquid in the container. To minimize this problem, some processing apparatus in the art use elaborate and expensive film entry and exit port closures or seals. Other apparatus use liquid surface passivating techniques such as floating a skim coat of mineral oil on top of the processing liquid. While this method may be effective, it is certainly awkward to implement when the fluid has to be changed.
Therefore, it is an object of the present invention to provide a processing apparatus, for immersion treating a film unit with a low viscosity processing liquid, that is convenient and easy to use.
Another object is to provide such a processing apparatus that is relatively inexpensive.
Yet another object is to provide such a processing apparatus which eliminates the need for the user having to fill or empty a liquid container forming part of the processing apparatus.
Still another object is to provide such a processing apparatus wherein components for squeegeeing excess liquid from the film unit do not come into direct contact with the liquid and therefore are not subject to being fouled by dryed out liquid or residue in the liquid.
Another object is to provide such a processing apparatus which includes a liquid container that is easily and inexpensively releasably sealed to minimize atmospheric contact with the liquid in the container.
Yet another object of the invention is to provide such a processing apparatus wherein a film receiving section forming part of the liquid container is adapted to remain in a flooded condition when the apparatus is not in use thereby minimizing contamination of the receiving chamber by dried out fluid or residue products in the liquid.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.